adverb (r)

• without delay or hesitation; with no time intervening(adv.all)

  Example:
  An official accused of dishonesty should be suspended forthwith.
  

  Synonym:
  at once, directly, immediately, instantly, like a shot, now, right away, straight off, straightaway
  

  source: wordnet30
• Immediately; without delay; directly.(adverb)

  source: webster1913